Method of enameling coil springs



Patented Dec, 9, 1924.

DAVID'MI Brian-Y, err BRISTOL, ANDLAWRENCEQ HUM-neon, or rnnrarnero'n; connnorrcnr; Assrenonsro rrrn ncivmson rannnracrumns COMPANY, OF ronnsrccnnncrrc'cr; a coerce-Arron or oon-nncrrcnr.

IIEETHGD 1 OF ENAEJIELING CDIIL SPRINGS.

No Drawing.

Be it known that we, DAVID M. BARRY and Lawiznucn G. I-lUarAsoN, citizens of the United States, and residents of Bristol and .i armington, respectively, county of Hartford, State of Connecticut, have invented certain new and useful Improvements in Methods of Enameling Coil Springs, of which the following is specification.

In the process of enameling coil springs, the convolutions of which are normally close together, it is preferable to stretch the spring in order to uniformly apply the enamel and then bake the enamel on the spring while the latter is in stretched condition to insure a uniform baking and an even coat. We have found, however, that the spring, when heated in a stretched condition to a temperature necessary to properly bake the enamel, takes an objectional set, which tends to twist or distort the spring.

The aim of the present invention is to provide an improved method of enameling wherein objectionable setting of the spring, resulting from baking the enamel while the spring is stretched, is prevented. To this end, the invention broadly contemplates initially heating the coil spring before applying the enamel and while the spring is in its normal or unstretched condition to a temperature in excess to that at which it is necessary to bake the enamel on the spring but not sutficiently high to draw the temper of the metal of the spring; then stretching the spring and applying the enamel thereon, and then baking the enamel while the spring is under tension. The temperature employed for initially heating the coil spring will depend of course on the composition of the metal used in the spring. By proceeding in accordance with the method of the present invention, the enamel is effectively and evenly applied and baked, insuring a neat, smooth finish and a rustproof coating, and undue setting or twisting of the spring is effectively guarded against. The step of initially heating the coil spring before applying the enamel and while the spring is in its normal or unstretched condition to a temperature in excess to that at which it is necessary to bake the enamel ou the spring prevents objectionable setting of the spring which would otherwise result Application filed December 23,.192L SerialNo. 524,543.

during the operation of baking the enamel while thespring is stretched.

The preferred method of procedure consists in heating the coiled wire in its normal condition (that is while it is not under tension or stretch) to a temperature higher than that required for baking the enamel on the coil but not suiiicientl' high to draw the temper of the metal of the sprin then stretching the coil and applying the enamel thereon in any suitable manner as by spraying or dipping; and then while the coil is stretched or extended, heating it until the enamel becomes tacky or set; then decreasing the extension or stretch of the spring but still holding it under tension, and finally heating the spr'ng in this condition, until the enamel becomes thoroughly hardened or baked, at a temperature less than that at which the spring was heated before the enamel was applied, but greater than that employed for heating the spring until the enamel becomes tacky or set. If desired, the wire, after it has been initially heated and before the enamel is app-lied, may be subjected to a suitable rust-proofing process, such as the Parkerizing process, but this is not necessary as theenamel itself will properly rust-proof the spring.

c have found that the method herein disclosed, while being susceptible of use in cnamcling coil springs generally, has peculia application in the enameling ot a coil spring the convolutions of which are fiat tened or elongated, for instance such S] 31"l1,.,2',

are used arm bands or garters.

We claim as our invention 1. That improvement in the art of enamch ing coil springs which consists in heating the coil spring in its normal condition, stretching said spring and applying the enamel, and then baking the enamel on the spring while the latter is under tension.

2. That improvement in the art of enameling coil springs which consists in heating the coil spring in its normal condition to a temperature higher than that necessary to bake the enamel on the spring, then stretching the spring and applying the enamel thereon, and then baking the enamel on the spring while the latter is under tension.

3. That improvement in the art of enanieh ing coil sprin s which consists in heating lt i) the spring to a temperature which will pre-- vent setting of the spring When it is subsequently heated to bake enamel thereon then applying the enamel with the spring in stretched condition and leaking the enamel onthe spring in stretched condition.

a. That improvement in the art of enan1el-. ing coil springs which consists in heating the spring in its normal condition to a temperature higher than that required for baking enamel on the spring, applying enamel to the spring and heating the spring in stretched condition until the enamel becomes tacky or set; then decreasing the stretch of the spring but still holding it under tension, 7

for heating the spring until the enamel be- 20 came tacky or set.

DAVID M. BARRY. LAWVRENCE C. HUMASON. 

